This happens from time to time but usually its temporarily, all images etc. should return after few minutes/hours, if not then report it to info@cgtrader.com
Tip: I noticed (in the past) the hang screen can keep reappearing when the site did some updates and my browser still has some old cookies, flushing them out worked for me. In this case it can indeed be a site issue but updating your browser or cleaning it out can often solve some issues.